Weld Sequence Planning for Major Assemblies - · PDF fileWeld Sequence Planning for Major Assemblies ... • Tack Welds / Spacing • Prepopulated ... weld beads for typical weld joints

Navy Metalworking Center A ManTech Center of Excellence

Advanced Metalworking Solutions for naval systems that go in harm’s way

Presented by Lori Denault (NMC/CTC)

On behalf of the Project Team

National Shipbuilding Research Program - All Panel Meeting March 07- 09, 2017

Weld Sequence Planning for Major Assemblies

Distribution Statement A: Approved for public release; distribution is unlimited. This material is submitted with the understanding that right of reproduction for governmental purposes is reserved for the Office of Naval

Research, Arlington, Virginia 22203-1995. This presentation was prepared by the Navy Metalworking Center, operated by Concurrent Technologies Corporation, under Contract No. N00014-10-D-0062 to the Office of

Naval Research as part of the Navy ManTech Program.

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Approved for public release (A); distribution unlimited

Manufacturing Issue

• The prevention and mitigation of weld-induced deformation creates a significant manufacturing challenge to the shop floor during fabrication of major ship assemblies

• Impacts cost and schedule • Preventing and correcting this weld deformation is done through

trial and error and involves significant labor hours (rework)• Weld sequence plans for major structures often do not exist• Trades weld structures according to tribal knowledge

• Detailed weld analyses can be carried out by experienced FEA analysts to identify critical areas or to prescribe distortion-reduction measures

• Often requires significant time (weeks or months) to set up and run the simulation and obtain useful results.

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Project Objective• Improve current weld sequence planning through the

development and use of a quick and user-friendly weld sequence planning tool (enhancement of commercially available software)

• Apply, validate, and implement the tool for common major tank assemblies at GDEB

• Mitigate shipbuilding costs associated with trial and error, welding and joint rework, and assembly flattening.

4ft x 4ft Sample Weldment Fabricated by NMC(17 parts, 42 weld joints, 220 individual weld passes)

NMC Weldment Contour Plot – Distortion (inches)

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Project Team• PMS 450 and PMS 397 – Stakeholder, oversight• Naval Surface Warfare Center, Carderock Division

(NSWCCD) Code 611 – Technical assistant, technical contribution

• General Dynamics Electric Boat (GDEB) – Technical contribution, testing and validation, implementation

• Navy Metalworking Center (NMC) – Project management, technical contribution

• Office of Naval Research (ONR) – Project funding and support

• ESI North America – Down-selected commercial partner for WSP Tool Development

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WSP Tool DevelopmentProject Approach

Requirements Document and

Sample ProblemSources Sought

Sample Problem Analysis and

RFP

Vendor Evaluation and

Down Select

Software Development,

Validation, and Implementation

• Documented tool capability and usability requirements

• Fabricated a physical weldment as a sample problem• The structure was

representative of a typical Navy structure

• This was done as a means to benchmark current software capabilities and functionality

• Used to gauge industry interest and capability

• Seven vendors responded. Many solutions:• Focused on

highly accurate joint level analysis solutions with full physics transient heat sources.

• Were limited in “higher level” distortion analysis of very large, complex structures

• Vendors asked to solve sample problem, provide results, and provide proposal to advance software to desired state

• Three vendors responded with proposed solutions with simplified approaches to balance accuracy vs. solution time for large, complex models

• ESI provided a full set of simulated measurements for all steps of fabrication

• ESI’s results most closely matched the trends and magnitudes of distortion exhibited by the physical weldment

• Advance software to meet shipyard needs

• Evaluate alpha and beta versions of the software, provide feedback

• Demonstrate software improvements at GDEB

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Initial Vendor Evaluation of Sample Problem

Comparison of maximum out-of-plane distortion for each surface of the structure, after each phase of construction

CAD geometry with measurement points and surface designations

ESI -to-physical (NMC) distortion contour plot comparison

Magnitude of Displacement

• ESI offered a simplified approach with accurate distortion trends and was down-selected to advance the ease of use of their tool.

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Purpose of the WSP Tool• WSP Tool Intent

• To develop sequencing plans for tank structure build plans at GDEB

– Output recommended weld sequence for minimum / allowable distortion – given realistic manufacturing constraints

• Quickly provide distortion trend data for a given geometry and weld joint configuration

Weld Joint Sequencing

• Properly streamlined and intuitive so that it allows the user to quickly investigate the effects of changes to sequencing, clamping, preheat, etc.

• Intended User • User with limited to no FEA experience

(but familiarity with CAD).

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Improvements Summary

* Estimated times based on ESI use of beta tool. Validation ongoing at NMC/GDEB.

Results available 5x faster

6 weeks1 week

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High Level Tool Overview

CAD Geometry(Siemens NX)

Weld Process Database

Material Database(ESI Visual Assembly)

Weld Process Plan (WPP)(Excel)

Meshing(ESI Visual Mesh)

Distortion Analysis(ESI Visual Assembly)

Optimization(ESI Visual Assembly)

Result Visualization(ESI Visual Viewer)

• Derived from Design Model

• Joint Trajectory Lines• No Edge Prep

• Part/Joint Information• Weld/Assembly Sequence• Tack Welds / Spacing

• Prepopulated• HSS, HSLA, HY• Filler Materials

• Prepopulated with Common MIL-STD-22D Joints

• General weld process information

• Shrinkage database

• Automatic Bead Creation/Placement

• Semiautomatic Meshing

• Clamp Locations

• Minimal User Input Req, Mainly Auto Populated

• Clamping Definitions• External Forces• Submit Analysis

• Blocking and initial sequence from WPP

• Define objective / critical tolerances• Max Number of iterations• Submit optimization

• Contours of distortion• Animations showing weld

sequence and movement• History Plots

Weld Sequence Plan(CSV / Text File)

• Best weld sequence obtained from Optimization

• Manually Incorporated into Work Package Instructions

User Inputs

WSP Tool Outputs

Solution Approach• Shrinkage method• No moving heat source, no

thermal calculations• Solid elements, no shells

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WSP Tool InputsGeometry

• Native CAD model can be used for geometry• Joint lines need to be added to the CAD model

– A reference and trajectory line need added for each joint line

• Creating edge prep geometry on joints is not necessary

• Adding root gaps is not necessary– Plates should be to be edge to edge

• Nx CAD was used as a direct interface for this project

• Direct interfaces with other CAD packages (Catia, Creo, Solidworks, etc.) are available

• Alternatively, STEP/IGES files can be used from any CAD package, but weld trajectories would need to be added in the ESI tool vs. the CAD package.

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WSP Tool InputsWeld Process Plan (WPP)

• The WPP is an Excel spreadsheet with detailed information for components and weld joints• It contains information such as joint name (J001), component names,

material designations, joint type, edge prep, fillet size, etc.• Initial weld sequence and blocking constraints for accessibility and

part flips can be defined in the WPP• The WPP is manually populated from existing GDEB data sources

• Scripts are being developed at GDEB to automatically populate the WPP.

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Weld Process Joint Database

The following MIL-STD-22D Joints are incorporated into the tool:PT2S.1, PT2V.2, PT2V.5, T2V.1, T2V.2, B2V.1, B2(S)V.2, PT2V.1, C1V.2,

C2V.2

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Meshing and Weld SetupWith v/s Without WSP Tool

Without WSP Tool With WSP Tool

Without WSP automation, meshing & model preparation can take

weeks to months

With WSP automation, meshing & model preparation takes

minutes to hours

• Cut geometry to add joint preparations• Manually calculate number of weld passes

per joint• Draw 2D cross sections of individual weld

beads for each joint• Extrude/sweep weld beads along trajectories• Split plate geometry to match weld joints for

structured mesh• Create structured mesh manually• Inspect mesh for errors or poor elements• Create groups and sets for weld material and

trajectories• Create and assign tack welds• Assign weld material to all welds and

structure• Assign weld process data manually for each

bead of every joint

• Populate weld process plan (WPP) spreadsheet from existing data

• Import CAD geometry and WPP• Automated joint/bead creation, mesh

generation, set/group assignment, tack welds, material assignment, and weld process assignment

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Automated MeshingLarge Assembly

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ResultsTypical Distortion Results

Distortion amplitude (inches) magnified 10x for visualization

Sequence Manager

Wel

d Pa

ss

Step

Initial Weld Sequence –Table of Runs

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Optimization• Optimization analysis is now possible with the WSP tool

• Optimization builds on previous runs

• Blocking capability is critical to practical optimization results• Otherwise, optimization may require part flips every other weld• Blocking also reduces the total number of variables and runtime

• Optimization uses a two layer optimization approach• Block Optimization: Get the best order of the blocks which minimizes

deformation• Weld Sequence: Based on the best block order, optimize the sequence

of the welds within the blocks to minimize deformation

• The output is a table of runs and a text file (csv file) with the best weld sequence.

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Optimization Results

Distortion amplitude (inches) magnified for visualization

~15% reduction in distortion amplitude

Initial Sequence Optimized Sequence

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Benefits• The Weld Sequence Planning tool is a commercially available

tool to help develop weld sequence/build plans • Uses a CAD-neutral approach for geometry and associated joint data • Reduces time to set-up, run, and obtain results by over 5x baseline

analysis• Allows for optimization of weld sequencing, clamping considerations• The WSP tool and training is available now for purchase from ESI

• Reduces the trial and error of distortion reduction predictions• Reduces distortion mitigation operations, improving throughput• Supports vision of driving toward a continuous flow of digital

information from the CAD model to shop floor production • Supports development of input necessary to implement robotic

welding initiatives.

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Near Term Activities

• GDEB is performing validation of a tank structure using the Weld Sequence Planning Tool • Documenting validation findings• Determining cost benefit and Return on Investment

• NMC is performing analyses and optimization on the sample problem – To confirm that the initial results match the results with the new

tool enhancements– To determine optimization recommendations.

• ESI is providing support through GDEB/NMC validation– Users Guide is being finalized by ESI

• The project team will document project results in a Project Final Report (June 2017).

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Future Enhancements• Enhancements Beyond This Project

• Additional Structure and Joint Types– Assemblies with structural shapes (I beams, C channels, angles,

etc.) are not currently compatible with automatic meshing– Other structures can still be analyzed and optimized with the

tool, but not with the full level of automation available for plate structures

– Recommend incorporation of deck - like structures next– Pre-Cambering is not easily modeled with the current tool– Expand database of MIL-STD-22D Joints

– B1V.2, B2V.3, B1S.1, B2S.1, B2U.3, B2U.4, and B2V.3• WSP output could directly feed into the inputs required

for robotic welding– Enable advancement of robotic welding

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Additional Information

• Lori Denault, CTC, (814) 269-6550• Charles Fisher, NSWCCD, (301) 227-4969• Yogendra Gooroochurn (San), ESI, (248) 381-8706• Jonathan Finley, GDEB, (401) 268-3578

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Additional Slides

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Areas of Software Development

CAD Import and Meshing

Automatic bead creation from user-defined weld trajectories (including multi-bead and multi-pass joints)

Quick meshing of weld beads for typical weld joints

Simpler meshing tools for semi-automated assembly meshing

Setup and Solution

Automated creation of tack welds using weld joints

Weld process database and automated joint/bead setup

Optimization

Create Optimization Workflow (Local Minima Distortion)

Blocking of variables and joints for optimization to represent stages of construction and address flipping/accessibility

Post Processing

Improvement and simplification of Visual-Viewer

Templates for easier post processing of distortion and shrinkage

Determination of desirable weld sequence

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Practical Usage of the WSP Tool• Intended for:

• Plate structures• Approximate distortion

magnitudes• Production planning/support• Distortion trend data• Weld sequencing• Part flips with gravity• Clamping evaluations• Preheating

• NOT intended for:• Structures with shapes (I

beams, channels, etc)• Exact distortion prediction• Transient analyses• Residual stress / fatigue• Detailed joint designs• Microstructure• Flame straightening• Precamber

• Very experienced FEA users can perform many of the “NOT intended” analyses with the existing software but will not benefit from all of the ease of use enhancements

• Future projects could expand the intended “simple mode” capabilities.

Documents

Weld Sequence Planning for Major Assemblies - · PDF fileWeld Sequence Planning for Major Assemblies ... • Tack Welds / Spacing • Prepopulated ... weld beads for typical weld joints